I'm still talking about restricted PvP though, not just toying with the element. They're far from mutually exclusive.
Quint is usually best in a duo, especially when you consider that Turquoise Nymph does its job better in the CC rush I've linked to earlier in this thread. There are exceptions, however: if you PU an opponent's creature, you might wanna Quint it. Or if you have several Turquoise Nymphs (I do), Quint can remove their only real weakness (one turn of vulnerability). Or if you use the Nymph to Quint Recluses (or other TU'd creatures), it works the same. There are many cards that work like this in many elements. Aether only has Quint that works like that.
Fractal also usually works better in a duo, as does PU in the unupped environment. The former still works well unupped though, so it seems to me your opinion is mostly spawned from the fact that two of its most powerful cards work best in a duo. Fact remains, however, that the other powerful cards (Phase Dragon, Dim Shield, Lightning) work just as well in a Mono, and if you look at other elements they will have just as many cards that work better in a duo. The difference is that these other-element cards don't stand out as much.
That's also the only difference. Aether's cards don't lack synergy; it's just that some of them are even better in a duo and you notice that much more since they're so powerful. Fractal, for instance, drains
for a reason. Balance.
Similarly, Quint is such a unique card it stands out.
As for another material creature, sure. If it has an interesting ability I'm all for it (middle-range attackers only make the elements less unique). That's not primarily what this thread is about though, but it would probably be more constructive if it was.
